Thermal switch

Abstract

A switch device utilizing independently acting biasing members to position a conductor to close a circuit between a pair of leads and maintain such closed circuit until a switch activating member such as a meltable pellet reaches a circuit opening state whereupon further independent biasing action causes the conductor member to assume a circuit open position.

What is claimed is: 
     
       1. A thermal switch comprising: a housing providing a cavity,   a pair of spaced electrical leads extending into said cavity in parallel through one end of said housing,   a conductor bar within said cavity for contacting the ends of said leads, to make electrical connection therebetween,   a mechanical isolating member surrounding said conductor bar between said leads and having parallel ends perpendicular to said leads, said conductor bar being movable within said isolating member between said parallel ends thereof and said isolating member being movable in said cavity parallel to said electrical leads,   a first compression spring within said isolating member urging said conductor bar toward the end of said isolating member nearest said one end of said cavity,   a second compression spring between said one end of said cavity and said isolating member urging said isolating member toward the end of said cavity opposite said one end, and   a fusible pellet between said isolating member and said opposite end of said cavity normally supporting said isolating member against the force of said second compression spring with said conductor bar contacting the ends of said electrical leads and being supported thereby away from the end of said isolating member against the force of said first compression spring.   
     
     
       2. The switch of claim 1 wherein said housing is thermally conductive and said fusible pellet is in thermally conductive contact with said housing. 
     
     
       3. The switch of claim 1 including insulating means for electrically insulating said leads from said housing. 
     
     
       4. The switch of claim 1 wherein said compression springs are in axial alignment.